JP4919192B2 - Transmission device, transmission method, and communication system - Google Patents

Description

  The present invention relates to a communication system for exchanging data exchanged between devices that store data collected from a plurality of communication devices, exchanging data with each other, and synchronizing the contents of the stored data. The present invention relates to a transmission apparatus, a transmission method, and a communication system that uses the transmission apparatus.

  In recent years, systems in which various functions are assigned to a plurality of communication devices, connected to each other, and exchange data with each other to perform various processes are used in various fields. For example, in the field of in-vehicle LAN (Local Area Network) distributed to vehicles, ECUs (Electronic Control Units) are used as communication devices, and each ECU performs specialized processing to mutually exchange data. By exchanging, various functions are realized as a system.

  As the functions of each communication device become special and the functions that can be performed by each communication device increase, the number and types of communication devices connected to the communication medium also increase. Furthermore, since various functions are expected as a system, it is necessary for each communication device to share and cooperate with each other, and the amount of data to be transmitted increases.

  Therefore, a configuration in which communication devices are divided into a plurality of groups and each group is connected to a communication medium is common. As a result, the number of communication devices connected to the communication medium is reduced, so the amount of communication can be reduced and data collisions can be avoided. In addition, in order to efficiently use communication media against an increase in the number of communication devices, there is a configuration in which groups of communication devices are classified according to the type of data to be transmitted and received and connected to communication media having different communication speeds for each group. In these configurations, different groups are connected by a gateway device that controls data transmission and reception.

In Patent Document 1, ECUs in the field of in-vehicle LAN are divided into a plurality of groups and connected to the in-vehicle communication line for each group, and the in-vehicle communication line is further connected by a gateway device, and priority is given to data to be transmitted and received. Priority information for identification is added, and when the gateway device transmits and receives data between different in-vehicle communication lines, priority is determined from the received data priority information and data with higher priority is transmitted preferentially However, a technique is disclosed in which transmission of data with high priority is not greatly delayed even when the communication load of the in-vehicle communication line increases.
JP 2005-159568 A

  When the communication devices are divided into a plurality of groups and each group is connected via a gateway device, each time data is transmitted from one group of communication devices to another group of communication devices, the gateway device is removed from the communication device. If data is transmitted to another communication device, the communication load between the communication devices cannot be reduced.

  Therefore, the data transmitted from each communication device is temporarily stored, and a plurality of transmission devices that further transmit to other communication devices are provided, and the data stored in each transmission device is periodically synchronized. Thus, the data stored from each transmission device can be transmitted at an efficient timing or an efficient combination without transferring the data transmitted from each communication device as it is, and the communication load can be reduced.

  In this case, it is assumed that the frequency at which each data is required in each communication device or the frequency at which the contents are updated differs for each type of data. Therefore, when synchronizing data between transmitting apparatuses, even if all data is transmitted and received, the contents of the data may not be updated or used.

  The present invention has been made in view of such circumstances, and is classified into groups for each type of stored data, and the data is further divided for each group and transmitted to other devices. Accordingly, an object of the present invention is to provide a transmission device, a transmission method, and a communication system using the transmission device that can efficiently exchange data and reduce a communication load.

  Another object of the present invention is to reduce the communication load and efficiently by adopting a configuration in which data is transmitted in a unit optimized so as not to exceed an allowable time for completing data transmission for each group. It is an object of the present invention to provide a transmission device capable of transmitting.

A transmission device according to a first aspect of the present invention is a storage unit that stores a plurality of data, a first transmission unit that transmits the data stored in the storage unit to one or a plurality of external devices mounted on the vehicle, A transmission mounted on the vehicle , comprising: means for storing data received from an external device in the storage means; and second transmission means for transmitting data stored in the storage means to the outside at a predetermined transmission cycle. In the apparatus, the means for classifying the data stored in the storage means into a plurality of groups, and the number of divisions of data for each group, the time corresponding to the product of the number obtained by adding 1 to the division number and the transmission period, Within a range in which the estimated transmission delay time for data to the external device and the estimated transmission delay time for data from the external device do not exceed the predetermined transmission completion allowable time for each group, Means for determining to be a large integer, and means for dividing the data for each group in the division number of said means is determined, each time the transmission period arrives, selecting for selecting the divided data for each group And the second transmission means transmits the data selected by the selection means.

  The transmitting apparatus according to the second invention is characterized in that the selecting means cyclically selects the divided data for each group.

A transmission method according to a third aspect of the present invention includes a storage unit that stores a plurality of data, a unit that transmits data stored in the storage unit to one or more external devices mounted on a vehicle, and the external device and means for storing the received data in the storage means respectively wherein the vehicle plurality of transmission devices mounted on transmits the data stored in the storage unit at a predetermined transmission period to another transmitting apparatus In the transmission method, each transmission device classifies the data stored in the storage means into a plurality of groups , and the number of divisions of data for each group is a product of the number obtained by adding 1 to the division number and the transmission period. The sum of the corresponding time, the estimated transmission delay time of data to the external device, and the estimated transmission delay time of data from the external device must not exceed the transmission completion allowable time predetermined for each group. Within, determined to be the maximum integer, determined by dividing the data for each group in the division number, each time the transmission period arrives, the divided data selected for each group, selected data Is transmitted.

A communication system according to a fourth aspect of the present invention is a storage means for storing a plurality of data, a first transmission means for transmitting the data stored in the storage means to one or a plurality of external devices mounted on the vehicle, A plurality of transmission devices mounted on the vehicle, each including a means for storing data received from an external device in the storage means and a second transmission means for transmitting data stored in the storage means ; Each transmitting device periodically transmits the data stored in the storage means to other transmitting devices at a predetermined transmission cycle and receives each other, and synchronizes the contents of the data stored in the respective storing devices. In this way, in each communication system, each transmission device classifies the data stored in the storage unit into a plurality of groups , and the number of data divisions for each group is a number obtained by adding 1 to the number of divisions. And transmission lap The time corresponding to the product of the above, the estimated transmission delay time of data to the external device, and the estimated transmission delay time of data from the external device exceed the allowable transmission completion time predetermined for each group. Means for determining to be the largest integer within a range, means for dividing the data for each group by the number of divisions determined by the means, and each time the transmission cycle arrives, the divided data is assigned to each group. Selecting means for selecting each time, and the second transmitting means transmits the data selected by the selecting means.

  In the present invention, data stored in the storage means is classified into groups, and the data is divided for each classified group. Each time the transmission cycle arrives, the data divided for each group is selected from the storage means and transmitted. The transmission of the data of each group is completed when the number of divisions × the transmission cycle has elapsed.

  In the present invention, the number of divisions is determined so that the time until all the data divided for each group is transmitted does not exceed the permissible transmission completion time predetermined for each group.

  In the case of the present invention, every time a transmission cycle arrives, all the data stored in the storage means is transmitted at a time, depending on the group, without being transmitted all at once. In this case, transmission of the data of each group is completed according to transmission cycle × number of divisions. Rather than transmitting data of a type that does not need to be updated frequently according to the transmission cycle, it is possible to efficiently transmit the data by changing the transmission completion cycle according to the cycle in which the data is to be updated. Also, depending on the group, the data is divided and transmitted multiple times, so that the amount of data transmitted in one transmission is reduced. Therefore, the communication load between the transmission devices can be reduced. Furthermore, by dividing and leveling and transmitting the data, it is possible to stably transmit and receive even when the allowable bandwidth of the communication medium connecting the transmission apparatuses is narrow.

  According to the present invention, it is possible to efficiently transmit data so that synchronization is periodically completed before the data transmission completion allowable time corresponding to the frequency required for each group and the frequency to be updated elapses. it can.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. In the following embodiments, a communication system according to the present invention will be described by taking an in-vehicle communication system applied to an in-vehicle LAN to which a plurality of ECUs that perform data transmission / reception processing are connected.

  FIG. 1 is a configuration diagram showing the configuration of the in-vehicle communication system in the present embodiment. The in-vehicle communication system includes ECUs (Electronic Control Units) 4a, 4a,..., 4b, 4b,..., 4c, 4c,. , 4c, 4c,..., 4c, 4c,..., 4c, 4c,... Are connected to the communication lines 3a, 3b, 3c, respectively. .., 4b, 4b,..., 4c, 4c,..., 4c, 4c,..., 4c, 4c, ..., and a communication line 2 connecting the distribution devices 1a, 1b, and 1c. The in-vehicle communication system according to the present embodiment includes ECUs 4a, 4a, ..., 4b, 4b, ..., 4c divided into a plurality of groups via distribution devices 1a, 1b, 1c connected to a communication line 2 serving as a trunk line. , 4c,... Constitutes a trunk type in-vehicle network.

  The connection form between the distribution devices 1a, 1b, and 1c via the communication line 2 is a daisy chain type in this embodiment. 4b, 4b,..., 4c, 4c,..., And distribution lines 1a, 1b, 1c via communication lines 3a, 3b, 3c are bus type, star type, daisy chain. Any form such as a mold may be used.

  The distribution devices 1a, 1b, and 1c have storage areas used as the databases 11a, 11b, and 11c, respectively. The distribution device 1a basically stores the data transmitted from the ECUs 4a, 4a... Connected to the communication line 3a in the database 11a, and transmits the data read from the database 11a to the ECUs 4a, 4a.

  The ECUs 4a, 4a,..., 4b, 4b,..., 4c, 4c,... Transmit data including numerical information of various physical quantities such as measured values, calculated values, control values, or are controlled by microcomputers such as engines and brakes. It is a possible device. For example, one ECU 4a functions as an ABS (Antilock Brake System) and is connected to a sensor (not shown) that detects the rotational speed (wheel speed) of the wheel. The one ECU 4a controls the brake based on the wheel speed detected via the sensor during braking of the vehicle, and transmits data including the measured value of the wheel speed to the distribution device 1a.

  The ECUs 4a, 4a, ..., 4b, 4b, ..., 4c, 4c, ... transmit data corresponding to different functions to the distribution devices 1a, 1b, 1c as described above. The data received from the ECU and stored in its own database by the distribution device is data transmitted from the ECU connected to the distribution device. Accordingly, the distribution devices 1a, 1b, and 1c are stored in the databases 11a, 11b, and 11c, respectively, and the types of data to be updated are different for the distribution devices 1a, 1b, and 1c.

  Accordingly, the wheel speed data transmitted from the ECU 4a is stored in the database 11a by the distribution device 1a, and the distribution device 1a updates the value each time it is received from the ECU 4a. However, the ECUs 4b, 4b, ..., 4c, 4c, ... connected to the other communication lines 3b, 3c may be used. Therefore, the distribution device 1a also stores the wheel speed data in the databases 11b and 11c of the other distribution devices 1b and 1c, and transmits the data to the ECUs 4b, 4b,..., 4c, 4c,. The distribution devices 1a, 1b, and 1c transmit data transmitted from the ECUs 4a, 4a,..., 4b, 4b,..., 4c, 4c, and so on to the other distribution devices 1a, 1b, and 1c. , 1c are received and stored in the respective databases 11a, 11b, 11c. As a result, the contents of the databases 11a, 11b, and 11c are synchronized, and the ECUs 4a, 4a, ..., 4b, 4b, ..., 4c, 4c, ... connected to different communication lines 3a, 3b, 3c have the same data. Can be used.

  Further, the distribution devices 1a, 1b, and 1c store data once and then transmit the data to the ECUs 4a, 4a,..., 4b, 4b,. , 4b, 4b,..., 4c, 4c,... Are optimized according to the processing in each ECU 4a, 4a,..., 4b, 4b,. , 4b, 4b,..., 4c, 4c,... Are combined and transmitted from the distribution devices 1a, 1b, 1c, or as necessary, the distribution devices 1a, 1b,. Transmission can be performed after 1c performs an operation on the data. Thus, since data can be efficiently transmitted from the distribution devices 1a, 1b, and 1c, the communication load on the communication lines 3a, 3b, and 3c can be reduced.

  FIG. 2 is a block diagram showing an internal configuration of distribution devices 1a, 1b, 1c and ECUs 4a, 4a,..., 4b, 4b,..., 4c, 4c,.

  The distribution device 1a includes a control unit 10a that controls the operation of each component shown below, a storage unit 12a that uses a volatile memory, a first communication control unit 13a that is connected to the communication line 3a, A second communication control unit 14 a connected to the line 2. Since the other distribution apparatuses 1b and 1c have the same internal configuration as the distribution apparatus 1a, detailed description thereof is omitted.

  The control unit 10a receives power supplied from a power supply device such as a vehicle alternator and battery (not shown), reads and executes a control program stored in a nonvolatile internal memory (not shown), and controls each component. .

  The storage unit 12a is provided with a storage area for a database 11a that records data received by the control unit 10a from the ECUs 4a, 4a,. The control unit 10a reads the corresponding specific measured value, calculated value, and control value from the received data for each type of data such as “wheel speed” and stores it in the database 11a.

  The first communication control unit 13a realizes data transmission / reception with the ECUs 4a, 4a,... Connected via the communication line 3a. The control unit 10a receives data from the ECUs 4a, 4a,... By the first communication control unit 13a, and transmits the data to the ECUs 4a, 4a,.

  Further, the second communication control unit 14a realizes data transmission / reception with other distribution devices 1b and 1c connected via the communication line 2. The control unit 10a transmits data read from the common area 12a in the database 11a by the second communication control unit 14a to the other distribution devices 1b and 1c, and receives data transmitted from the other distribution devices 1b and 1c. To do.

  The ECU 4a includes a control unit 40 that controls the operation of each component shown below, a storage unit 41 that uses a nonvolatile memory, a communication control unit 42 connected to the communication line 3a, and a sensor (not shown). An input unit 43 that inputs a signal and an output unit 44 that outputs a control signal to a control target device (not shown) are provided. Since the other ECUs 4b and 4c have the same configuration as the ECU 4a, detailed description thereof is omitted. Note that, depending on the ECUs 4a, 4b, and 4c, only one of the input unit 43 and the output unit 44 may be provided.

  The control unit 40 of the ECU 4a receives power supplied from a power supply device such as a vehicle alternator and a battery (not shown) and detects a signal representing a measurement value from a sensor (not shown) connected to the ECU 4a via the input unit 43. Then, the control signal is transmitted to the device to be controlled connected to the ECU 4 a via the output unit 44.

  The storage unit 41 temporarily stores various information generated in the process of the control unit 40 or measurement values represented by signals input from, for example, a sensor (not shown).

  The communication control unit 42 has a network controller chip or a network controller function, and realizes communication with the communication line 3a. The control unit 40 of the ECU 4a detects a signal from a sensor (not shown) at regular intervals of 1 millisecond, for example, and transmits data including a numerical value of a physical quantity indicated by the detected signal via the communication control unit 42. The control unit 40 of the ECU 4a receives data transmitted from the distribution device 1a via the communication control unit 42.

  In the in-vehicle communication system configured as described above, a process will be described in which the distribution apparatuses 1a, 1b, and 1c exchange data by transmitting and receiving data in order to synchronize the contents of the databases 11a, 11b, and 11c.

  FIG. 3 is an explanatory diagram schematically showing the contents of data exchanged between the distribution devices 1a, 1b, and 1c constituting the in-vehicle communication system in the present embodiment. In the explanatory diagram of FIG. 3, the horizontal axis represents time, and the contents of data transmitted and received by the distribution devices 1a, 1b, and 1c at each time point are schematically shown. Each rectangle shown in the explanatory diagram of FIG. 3 represents a data group read from the databases 11a, 11b, and 11c, and the codes A, B, and C in each rectangle are updated by the distribution devices 1a, 1b, and 1c, respectively. Data groups to be distinguished.

  First, the distribution devices 1a, 1b, and 1c basically transmit the data group read from the databases 11a, 11b, and 11c to the other distribution devices 1a, 1b, and 1c according to a predetermined transmission cycle. In this embodiment, the transmission cycle is set to 200 milliseconds, for example.

  Distribution devices 1a, 1b, and 1c in the present embodiment are connected in a daisy chain type as described above. Therefore, as shown in the explanatory diagram of FIG. 3, when the synchronization process is performed from the distribution device 1a, the distribution device 1a transmits the data group read from the database 11a to the distribution device 1b every time the transmission cycle arrives. At this time, the data group A updated by the distribution device 1a in the data transmitted from the distribution device 1a to the distribution device 1b is updated to the latest value. The distribution device 1b writes the data group B read from its own database 11b to the data received from the distribution device 1a, and transmits it to the distribution device 1c. At this time, the distribution device 1b does not write data in the area of the data group A updated by the distribution device 1a. Further, the distribution device 1c writes the data group C read from the database 11c to the data received from the distribution device 1b. As a result, the data group transmitted from the distribution device 1a to the distribution device 1b and from the distribution device 1b to the distribution device 1c is a data group having new values in the databases 11a, 11b, and 11c.

  Next, the distribution device 1c updates the database 11c based on the data group after the data group C read from the database 11c is written. At this time, the distribution device 1c may read data from the areas of the data groups A and B updated by the distribution devices 1a and 1b in the updated data and write them into the database 11c, or the data group read from the database 11c. Before writing C, data may be read from the areas of the data groups A and B updated by the distribution devices 1a and 1b and written to the database 11c. Next, the distribution apparatus 1c transmits a data group having new values in all the databases 11a, 11b, and 11c so as to return it to the distribution apparatus 1b. The distribution device 1b updates the database 11b based on the data group received from the distribution device 1c, and further transmits the received data group to the distribution device 1a. The distribution device 1a updates the database 11a based on the data group received from the distribution device 1b.

  Each of the distribution devices 1a, 1b, and 1c executes a process of transmitting and receiving a data group as shown in the explanatory diagram of FIG. 3 every time a transmission cycle of 200 milliseconds arrives.

  By the way, the data stored in the databases 11a, 11b, 11c are data to be transmitted to the ECUs 4a, 4a,..., 4b, 4b,. Depending on the type of data, data that needs to be updated every 500 milliseconds according to the processing of ECUs 4a, 4a,..., 4b, 4b,. There are various types of data that need only be updated. For example, wheel speed data needs to be updated every 500 milliseconds, while room temperature data may need to be updated every 3 seconds.

  On the other hand, when the data groups read and transmitted from the distribution devices 1a, 1b, and 1c shown in the explanatory diagram of FIG. 3 are all the data groups that are updated respectively, the data groups are updated every 3 seconds. In this case, sufficient types of data are transmitted to each of the distribution devices 1a, 1b, and 1c for synchronization every time although the values are not updated. In this case, an extra communication band of the communication line 2 that connects the distribution devices 1a, 1b, and 1c is used.

  In the distribution devices 1a, 1b, and 1c in the present embodiment, data is transmitted to the distribution devices 1a, 1b, and 1c from the ECUs 4a, 4a,..., 4b, 4b,. , 1b, 1c, and the databases 11a, 11b, 11b, 11b, 11b, 11b, 11c, 11b, 11b, and 11b, according to the delay allowable time considering the delay required for transmission to the ECUs 4a, 4a, ..., 4b, 4b, ..., 4c, 4c, ... The data stored in 11c is classified into groups. .., 4b, 4b,..., 4c, 4c,... From the ECUs 4a, 4a,..., 4b, 4b,. Should be sent to 4c, 4c,. Accordingly, the distribution devices 1a, 1b, and 1c divide the data of the group having a long allowable delay time into a plurality of times without transmitting each time the transmission period for synchronization arrives, and transmit the data a plurality of times.

  FIG. 4 is a diagram illustrating an example of the content of the allowable delay time of data transmitted and received between the distribution devices 1a, 1b, 1c and the ECUs 4a, 4a,..., 4b, 4b, ..., 4c, 4c,. FIG. FIG. 4A shows that the delay time for each data and the group classified by the allowable delay time are associated with each other. FIG. 4 (b) shows the number of data belonging to each group when classified as shown in FIG. 4 (a).

  As shown in FIG. 4A, the allowable delay time varies depending on each data. In the case of the content example shown in the explanatory diagram of FIG. 4A, “500 milliseconds” of “data 1” is the shortest. .., 4b, 4b,..., 4c, 4c,... To the distribution devices 1a, 1b, 1c, and from the distribution devices 1a, 1b, 1c to the respective ECUs 4a, 4a,. , 4c,..., 4c,... Should be transmitted for synchronization every time a transmission period of 200 milliseconds elapses. Here, when all the data is transmitted at once for synchronization, it must be matched with the data having the shortest allowable delay time.

  However, in this embodiment, the data stored in the databases 11a, 11b, and 11c are classified into groups as described above. In the example of contents shown in FIG. 4A, data is classified into three groups X, Y, and Z with allowable delay times of “500 milliseconds”, “1000 milliseconds”, and “3000 milliseconds”, respectively. In the example of contents shown in FIG. 4A, data whose allowable delay time is less than “1000 milliseconds” is in group X, and data whose allowable delay time is “1000 milliseconds” or more and less than “3000 milliseconds” is group Y. In addition, it is shown that the data whose delay allowable time is “3000 milliseconds” or more is classified into the group Z.

  In FIG. 4B, among the “100” data stored in the databases 11a, 11b, and 11c, “20” data is classified into the group X whose delay allowable time is “500 milliseconds”. “35” data is classified into the group Y with the allowable delay time “1000 milliseconds”, and “45” data is classified into the group Z with the allowable delay time “3000 milliseconds”. It has been shown.

  Note that the data structures of the databases 11a, 11b, and 11c themselves may be arranged in advance in the order shown in FIG. FIG. 5 is an explanatory diagram showing an example of the data structure of the databases 11a, 11b, and 11c of the distribution devices 1a, 1b, and 1c in the present embodiment. In the explanatory diagram of FIG. 5, the data structures of the databases 11a, 11b, and 11c stored in the storage units 12a, 12b, and 12c of the distribution devices 1a, 1b, and 1c are stored in the order of groups X, Y, and Z, respectively. It is shown that it is configured to continue. Since the databases 11a, 11b, and 11c are configured as shown in the explanatory diagram of FIG. 5, the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c By storing the address of the head data of each group and the number of data (total size) of each group, it is possible to easily read data for each group.

  In the process of classifying each data into groups, group information as shown in the explanatory diagram of FIG. 4A may be stored in advance in the storage units 12a, 12b, and 12c. As shown, the structure of the databases 11a, 11b, and 11c may be configured such that the area is divided in advance for each group. However, the present invention is not limited to this, and a configuration in which the control unit 10a of the distribution device 1a dynamically executes the process of classifying each data into groups may be employed.

  FIG. 6 is a flowchart illustrating an example of a processing procedure in which data is classified into groups by the control unit 10a of the distribution device 1a according to the present embodiment.

  The control unit 10a of the distribution device 1a determines whether or not the allowable delay time given to the data is less than the first threshold “1000 milliseconds” (step S11). When the control unit 10a determines that the given allowable delay time is less than the first threshold (S11: YES), the control unit 10a classifies the shortest time among the allowable delay times into the group X having the allowable delay time ( In step S12), the classified group X is stored in association with the data (step S13).

  When it is determined that the given allowable delay time is equal to or greater than the first threshold (S11: NO), the control unit 10a determines whether the allowable delay time is less than the second threshold “3000 milliseconds”. (Step S14). When determining that the allowable delay time is less than the second threshold (S14: YES), the control unit 10a classifies the first threshold into the group Y having the allowable delay time (step S15), and classifies the data as the data. The group Y is stored in association with each other (S13).

  When the control unit 10a determines that the given allowable delay time is equal to or greater than the second threshold (S14: NO), the control unit 10a classifies the second threshold into the group Z having the allowable delay time (step S16). The group Z classified as data is stored in association with each other (S13).

  Next, the control unit 10a determines whether or not all data has been classified (step S17). If it is determined that all data has not been classified (S17: NO), the process returns to step S11 to return to the next data. A classification process is performed for. If the control unit 10a determines that all data has been classified (S17: YES), the process is terminated.

  The control unit 10a of the distribution device 1a executes the processing shown in the flowchart of FIG. 6 to obtain information associated with groups as shown in FIG. 6 is executed by the control unit 10a of the distribution device 1a, the address of the head data of each group in the database 11a having the structure shown in the explanatory diagram of FIG. 5 is stored in the storage unit 12a. The structure may be stored. Similarly, the control units 10b and 10c of the distribution devices 1b and 1c may perform the processing shown in the flowchart of FIG. 6 or may transmit the information obtained by the distribution device 1a to the distribution devices 1b and 1c.

  Next, a process in which the distribution devices 1a, 1b, and 1c read and transmit data from the databases 11a, 11b, and 11c for each group classified as described above will be described. Note that the allowable delay time of data classified into groups X, Y, and Z with respect to a transmission cycle of 200 milliseconds is “500 milliseconds”, “1000 milliseconds”, and “3000 milliseconds”. Distribution devices 1a, 1b, and 1c divide a data group for each group that has been classified, and transmit the divided data group multiple times.

  The division number d for dividing the data group for each group is determined so as to satisfy the condition shown in Expression (1).

  (Division number d + 1) × (transmission cycle) + (expected transmission delay time from ECUs 4a, 4a,..., 4b, 4b,..., 4c, 4c,...) + (ECUs 4a, 4a,..., 4b, 4b,. 4c, 4c,... (Expected transmission delay time) ≦ (Group delay allowable time) (1)

  In the case of the in-vehicle communication system according to the present embodiment, the estimated transmission delay time between the distribution devices 1a, 1b, 1c and the ECUs 4a, 4a,..., 4b, 4b,. ”Is considered, the conditions for determining the division numbers dx, dy, dz for dividing the data of the groups X, Y, Z are derived as shown in equations (2) to (7).

  (Dx + 1) × 200 + 50 + 50 ≦ 500 (2)

  dx ≦ 1 (3)

  (Dy + 1) × 200 + 50 + 50 ≦ 1000 (4)

  dy ≦ 3.5 (5)

  (Dz + 1) × 200 + 50 + 50 ≦ 3000 (6)

  dz ≦ 13.5 (7)

  The division number dx of the data of the group X is determined to be “1” so as to satisfy the conditions derived as in Expressions (3), (5), and (7). Further, the division number dy of the data of the group Y is determined to be “3”, for example, and the division number dz of the data of the group Z is determined to be “10”. The maximum integer that satisfies the condition may be determined as the number of divisions, but the data division number dz of the group Z is determined to be “10” if the condition is satisfied even if the number of divisions exceeds 10. The configuration.

  When the division numbers dx, dy, dz for each group are determined, the control units 10a, 10b, 10c of the distribution devices 1a, 1b, 1c divide the data group of each group by the division numbers dx, dy, dz. In addition, the number of data to be read for each transmission cycle is calculated.

  FIG. 7 is a flowchart illustrating a processing procedure in which the number of divisions for each group is determined by the control unit 10a of the distribution device 1a according to the present embodiment and the number of data to be read is calculated. The control unit 10a of the distribution device 1a reads the information shown in FIG. 4B from the storage unit 12a and executes the following processing. The control units 10b and 10c of the distribution devices 1b and 1c may perform the same process, or may be configured to acquire information determined and calculated by the control unit 10a of the distribution device 1a.

  The control unit 10a of the distribution device 1a reads the allowable delay time for each group (step S21), and determines the number of divisions according to the above equation (1) (step S22). The control unit 10a reads the number of data classified into each group (step S23), and divides the number of data by the determined number of divisions (rounds up in the positive infinity direction), thereby obtaining the number of data to be read when transmitting. Calculate (step S24). The control unit 10a stores the determined number of divisions and the calculated number of data in the storage unit 12a (step S25), and ends the process.

  FIG. 8 is an explanatory diagram illustrating a content example of the number of divisions determined and stored by the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c and the number of data to be read in the present embodiment. The content example shown in the explanatory diagram of FIG. 8 corresponds to the content example shown in FIG. 4B and corresponds to the result of executing the processing shown in the flowchart of FIG.

  In the content example shown in the explanatory diagram of FIG. 8, since the number of data belonging to the group X is “20” and the division number dx is determined to be “1”, each time the transmission cycle arrives, the control units 10a, 10b, 10c indicates that all “20” data belonging to group X should be read. Further, since the number of data belonging to the group Y is “35” and the division number dy is “3”, the control units 10a, 10b, and 10c have “12” pieces of data belonging to the group Y every time the transmission cycle arrives. It is shown that it should be read out one by one. Similarly, since the number of data belonging to group Z is “45” and the division number dz is “10”, each time the transmission cycle arrives, the control units 10a, 10b, and 10c transfer the data belonging to group Z to “5”. It is shown that they should be read one by one. When the control units 10a, 10b, and 10c read the data of the groups Y and Z, respectively, since the data for the calculated number of data cannot be read at the final time, the remaining data is read.

  When the databases 11a, 11b, and 11c are classified and transmitted / received as they are without being divided between the distribution apparatuses 1a, 1b, and 1c, the total number of data is “100 (= 20 + 35 + 45)”. Therefore, every time the transmission cycle arrives, “100” data is transmitted to the communication line 2. However, in the case of the present invention, the data groups stored in the databases 11a, 11b, and 11c are classified into groups, and are further divided into groups for transmission. Therefore, the number of data transmitted in one transmission is “37 (= 20 + 12 + 5)”. Thereby, the communication load in the communication line 2 is reduced.

  In the present embodiment, the division numbers dx, dy, and dz are determined in Expression (1) by the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c, as shown in the explanatory diagram of FIG. The information is stored. However, the present invention is not limited to this, and each may be stored in advance in the storage units 12a, 12b, and 12c together with the information shown in the explanatory diagrams of FIGS.

  Next, transmission processing between the distribution apparatuses 1a, 1b, and 1c will be described. The control unit 10a of the distribution device 1a according to the present embodiment cyclically selects and transmits the divided data for each group as shown in the explanatory diagram of FIG. 8 every time the transmission cycle arrives.

  FIG. 9 is a flowchart showing a processing procedure in which the control unit 10a of the distribution apparatus 1a according to the present embodiment transmits data read from the database 11a to the other distribution apparatuses 1b and 1c for synchronization. Since the control units 10b and 10c of the distribution devices 1b and 1c perform the same processing as the distribution device 1a, detailed description thereof is omitted.

  The control unit 10a of the distribution device 1a determines whether or not the transmission cycle has arrived (step S31). When it is determined that the transmission cycle has not arrived (S31: NO), the control unit 10a returns the process to step S31 and waits until it is determined that the transmission cycle has arrived.

  When it is determined that the transmission cycle has arrived (S31: YES), the control unit 10a selects data divided according to the number of divisions for each classified group in the database 11a (step S32). At this time, as illustrated in the explanatory diagram of FIG. 8, the control unit 10a selects data according to the number of data read at the time of one transmission calculated by determining the division number dx.

  Next, the control unit 10a transmits the data selected for each group to the other distribution devices 1b and 1c by the second communication control unit 14a (step S33), and ends the transmission process.

  The control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c in the present embodiment repeat the processing shown in the flowchart of FIG. 9 every time a transmission cycle of 200 milliseconds arrives.

  FIG. 10 is an explanatory diagram schematically showing an example of the contents of data divided for each classified group by the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c in the present embodiment. The explanatory diagram of FIG. 10 corresponds to the case where the data structures of the databases 11a, 11b, and 11c are configured for each group as shown in the explanatory diagram of FIG. The explanatory diagram of FIG. 10 shows that the data is divided by dividing the area in which the data groups classified into the groups X, Y, and Z are stored. Each area is divided so as to include data for the calculated number of data to be read.

  As shown in the explanatory diagram of FIG. 10, the data group of the group X in the databases 11a, 11b, and 11c is not divided because the division number dx is “1”, and is transmitted every time a transmission period of 200 milliseconds arrives. . The group Y data group is divided into three areas “Y0”, “Y1”, and “Y2” because the division number dy is “3”. Since the data group D has a division number dz of “10”, “Z0”, “Z1”, “Z2”, “Z3”, “Z4”, “Z5”, “Z6”, “Z7”, “ The area is divided into 10 areas “Z8” and “Z9”.

  As shown in the explanatory diagram of FIG. 10, the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c keep the data structures of the databases 11a, 11b, and 11c as groups. The top addresses of the data groups divided into two may be stored. Thereby, when transmitting data, the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c divide each group by selecting the head address of the data group that is cyclically divided for each group. Reading of the processed data can be facilitated.

  For example, the control unit 10a of the distribution device 1a selects and transmits all of the group X, the data group of the “Y0” area of the group Y, and the data group of the “Z0” area of the group Z for the first transmission. . In addition, the control unit 10a selects and transmits all of the group X, the data group of the “Y2” area of the group Y, and the data group of the “Z2” area of the group Z for the third transmission. The control unit 10a selects and transmits all of the group X, the data group of the “Y0” area of the group Y, and the data group of the “Z3” area of the group Z at the fourth transmission.

  The distribution apparatus 1b that has received the data group including all of the group X transmitted from the distribution apparatus 1a, the data group of the “Y0” area of the group Y, and the data group of the “Z0” area of the group Z is: Of the data group in the “Y0” area of group X and group Y and the data group in the “Z0” area of group Z, a data group that is received and updated by ECU 1b, 4b,. To the distribution device 1c. In the distribution device 1c, the distribution device 1c in each of the data group in the “Y0” area of the group X and the group Y and the data group in the “Z0” area of the group Z receives and updates from the ECUs 4c, 4c,. Write the data group and loop back to the distribution device 1b.

  As described above, when the data divided for each group is selected and transmitted every time the transmission cycle arrives from the distribution devices 1a, 1b, and 1c, the amount of data transmitted in one transmission cycle is the database 11a. , 11b and 11c are reduced as compared to the case where all of them are transmitted.

  FIG. 11 is a schematic diagram schematically showing data transmitted / received for synchronization between distribution apparatuses 1a, 1b, and 1c in the present embodiment. FIG. 11A shows a data group in a case where all the data stored in the databases 11a, 11b, and 11c are transmitted and received at every transmission cycle. On the other hand, FIG. 11B shows a data group when data stored in the databases 11a, 11b, and 11c is classified into groups, and the data is transmitted by being divided into groups. In both FIGS. 11A and 11B, the horizontal axis represents the passage of time, and the scale is tuned every 200 milliseconds.

  As shown in FIG. 11A, when all the data stored in the databases 11a, 11b, and 11c are transmitted, all are transmitted and received between the distribution devices 1a, 1b, and 1c every 200 milliseconds. In the data group transmitted / received every 200 milliseconds, it is sufficient that the data is updated every 3 seconds and the delay allowable time is 3000 milliseconds. When all data is transmitted / received every 200 milliseconds, such data is also transmitted / received every 200 milliseconds, and extra data is transmitted / received.

  On the other hand, as shown in FIG. 11 (b), when the data stored in the databases 11a, 11b, and 11c are classified into groups, and divided into different numbers of divisions for each classified group, a plurality of data are transmitted. The amount of data transmitted and received at one time between the distribution devices 1a, 1b, and 1c every 200 milliseconds in the transmission cycle is reduced as compared with the case of transmitting and receiving all of FIG. Thereby, extra transmission / reception in the communication line 2 can be reduced, and a communication load can be reduced. Further, the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c in the present embodiment determine the number of divisions, and calculate the number of data to be read each time by simply dividing the number of data for each group by the number of divisions. did. Therefore, every time the transmission cycle arrives, the amount of data transmitted and received by the distribution devices 1a, 1b, and 1c is leveled, and stable transmission / reception is performed even when the communication line 2 having a relatively narrow communication band is used. I can expect that.

  As shown in FIG. 11B, the control units 10a, 10b, and 10c of the distribution devices 1a, 1b, and 1c in the present embodiment determine the number of divisions and set the number of data to be read each time to the number of data for each group. Is simply divided by the number of divisions, the amount of data transmitted and received by the distribution devices 1a, 1b, and 1c is leveled each time the transmission period arrives. However, the present invention is not limited to this, and it is not essential that the amount of data to be transmitted is leveled every time the transmission cycle arrives. For each group, the entire databases 11a, 11b, and 11c are not transmitted and received. The data amount is reduced within a range not exceeding the allowable delay time and transmitted.

  Further, the number of data divisions in each group is determined so as to satisfy the condition of Expression (1) so as not to exceed the allowable transmission delay time of each group. In this embodiment, since the data group of group Y is transmitted three times, transmission is completed every three transmission cycles, that is, every 200 milliseconds × 3 = 600 milliseconds. ECU 4a, 4a, ..., 4b, 4b, ..., 4c, 4c, ... to distribution devices 1a, 1b, 1c, and distribution devices 1a, 1b, 1c to ECUs 4a, 4a, ..., 4b, 4b, ..., 4c, 4c ,... And transmission and reception are completed in a sufficient cycle with respect to the allowable delay time “1000 milliseconds” of the data group of group Y, even if the time required for transmission to and the expected delay time in that case are considered.

  Similarly, since the data group of group Z is divided into 10 and transmitted 10 times, transmission is completed every 10 transmission cycles, that is, every 200 milliseconds × 10 = 2000 milliseconds. Transmission / reception is completed with a sufficient period with respect to the delay allowable time “3000 milliseconds” of the data group of group Z.

  As described above, according to the present invention, when data is transmitted periodically, all data is not transmitted every time, and the transmission completion period is made variable for each group within a range not exceeding the allowable transmission delay. The amount of data to be transmitted can be reduced. Accordingly, the distribution devices 1a, 1b, and 1c can efficiently transmit and receive data, reduce the amount of data transmitted and received through the communication line 2, and reduce the communication load.

  In the communication system according to the present embodiment, the distribution devices 1a, 1b, and 1c are connected by a daisy chain type. Further, the distribution device 1b that receives the data group transmitted from the distribution device 1a writes the data to the area of the data group to be updated by the distribution device 1a in order to synchronize data between the distribution devices 1a, 1b, and 1c. Then, the distribution apparatus 1c that has transmitted to and received the distribution apparatus 1c further writes data to the area of the data group to be updated by itself, and loops back to the distribution apparatuses 1b and 1a in order. However, the transmission / reception procedure in the present invention is not limited to this, and the distribution apparatuses 1a, 1b, and 1c are connected in a bus type, and each time the transmission cycle arrives, the distribution apparatuses 1a, 1b, and 1c are sequentially turned into their own databases. Of the data stored in 11a, 11b, 11c, a data group divided for each group may be selected and transmitted to the other distribution devices 1a, 1b, 1c.

It is a block diagram which shows the structure of the vehicle-mounted communication system in this Embodiment. It is a block diagram which shows the internal structure of distribution device and ECU which comprise the vehicle-mounted communication system in this Embodiment. It is explanatory drawing which shows typically the content of the data exchanged between the distribution apparatuses which comprise the vehicle-mounted communication system in this Embodiment. It is explanatory drawing which shows the example of the content of the delay allowable time of the data transmitted / received between the distribution apparatus and ECU in this Embodiment. It is explanatory drawing which shows the example of the data structure of the database of the distribution apparatus in this Embodiment. It is a flowchart which shows an example of the process sequence in which data is classified into a group by the control part of the distribution apparatus in this Embodiment. It is a flowchart which shows the process sequence by which the division | segmentation number for every group is determined by the control part of the distribution apparatus in this Embodiment, and the data number which should be read is calculated. It is explanatory drawing which shows the example of the content of the division | segmentation number determined and memorize | stored by the control part of the distribution apparatus in this Embodiment, and the number of data to read. It is a flowchart which shows the process sequence which the control part of the distribution apparatus in this Embodiment transmits the data read from the database to another distribution apparatus for a synchronization. It is explanatory drawing which shows typically the example of the content of the data divided | segmented for every group classified by the control part of the distribution apparatus in this Embodiment. It is a schematic diagram which shows typically the data transmitted / received for the synchronization between the distribution apparatuses in this Embodiment.

Explanation of symbols

1a, 1b, 1c Distribution device (transmission device)
10a, 10b, 10c Control unit 11a, 11b, 11c Database 12a, 12b, 12c Storage unit 4a, 4b, 4c ECU

Claims (4)

Storage means for storing a plurality of data, first transmission means for transmitting data stored in the storage means to one or a plurality of external devices mounted on the vehicle, and storage of data received from the external devices Means for storing in the means, and second transmission means for transmitting data stored in the storage means to the outside at a predetermined transmission cycle, and in a transmission device mounted on the vehicle ,
Means for classifying the data stored in the storage means into a plurality of groups;
The number of data divisions per group is a time corresponding to the product of the number obtained by adding 1 to the number of divisions and the transmission period, the estimated data transmission delay time to the external device, and the data transmission delay from the external device Means for determining the sum of the expected times to be a maximum integer within a range not exceeding a transmission completion allowable time predetermined for each group;
Means for dividing the data into groups by the number of divisions determined by the means;
Selection means for selecting the divided data for each group each time the transmission cycle arrives,
The transmission apparatus according to claim 2, wherein the second transmission unit transmits the data selected by the selection unit.   2. The transmission apparatus according to claim 1, wherein the selection unit is configured to cyclically select the divided data for each group. Storage means for storing a plurality of data, means for transmitting data stored in the storage means to one or more external devices mounted on a vehicle, and storing data received from the external devices in the storage means comprising respectively and means for a plurality of transmission devices mounted on the vehicle, the transmission method for transmitting data stored in the storage unit at a predetermined transmission period to another transmitting apparatus,
Each transmitting device
Classifying the data stored in the storage means into a plurality of groups ;
The number of data divisions per group is a time corresponding to the product of the number obtained by adding 1 to the number of divisions and the transmission period, the estimated data transmission delay time to the external device, and the data transmission delay from the external device The total time of the expected time is determined to be the largest integer within a range not exceeding the transmission completion allowable time predetermined for each group,
Divide the data into groups with the determined number of divisions,
Each time the transmission cycle arrives, select the divided data for each group,
A transmission method characterized by transmitting selected data. Storage means for storing a plurality of data, first transmission means for transmitting data stored in the storage means to one or a plurality of external devices mounted on the vehicle, and storage of data received from the external devices and means for storing the unit, said second transmission means for transmitting each comprise a data stored in the storage means includes a plurality of transmission devices mounted on the vehicle, each of the transmitting apparatus at a predetermined transmission cycle In the communication system in which the data stored in the storage means is periodically transmitted to other transmission devices and mutually received, and the contents of the data stored in the respective storage means are synchronized,
Each transmitting device
Means for classifying the data stored in the storage means into a plurality of groups;
The number of data divisions per group is a time corresponding to the product of the number obtained by adding 1 to the number of divisions and the transmission period, the estimated data transmission delay time to the external device, and the data transmission delay from the external device Means for determining the sum of the expected times to be a maximum integer within a range not exceeding a transmission completion allowable time predetermined for each group;
Means for dividing the data into groups by the number of divisions determined by the means;
Selection means for selecting the divided data for each group each time the transmission cycle arrives,
The communication system, wherein the second transmission means transmits data selected by the selection means.

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